How the DES_ENCRYPT() function works in Mariadb?

The DES_ENCRYPT() function is a string function that encrypts a string using the Data Encryption Standard (DES) algorithm, which is a symmetric-key block cipher. It is useful for protecting sensitive data, such as passwords, credit card numbers, or personal information.

Syntax

The syntax of the DES_ENCRYPT() function is as follows:

DES_ENCRYPT(str [,key_str])

The str parameter is a string that represents the data to be encrypted. The key_str parameter is an optional string that specifies the key to use for encryption. If the key_str parameter is omitted, the DES_ENCRYPT() function uses a default key that is stored in the des_key_file system variable.

The DES_ENCRYPT() function returns a binary string that represents the encrypted data. If the str parameter is NULL, the DES_ENCRYPT() function returns NULL.

Examples

Example 1: Encrypting a string with a key

In this example, we use the DES_ENCRYPT() function to encrypt a string with a key. We assume that the des_key_file system variable is set to a file that contains the key.

-- Set a key
SET @key = 'secret';

-- Encrypt a string with the key
SET @plain = 'Hello, world!';
SET @crypt = DES_ENCRYPT(@plain, @key);

-- Display the encrypted string
SELECT HEX(@crypt) AS encrypted;

The output is:

+------------------------------------+
| encrypted                          |
+------------------------------------+
| FF0C3106190559A697906CA4CDF6CB56AE |
+------------------------------------+

The DES_ENCRYPT() function returns a binary string that can be decrypted using the DES_DECRYPT() function with the same key.

Example 2: Encrypting a string without a key

In this example, we use the DES_ENCRYPT() function to encrypt a string without a key. We assume that the des_key_file system variable is set to a file that contains the key.

-- Encrypt a string without a key
SET @plain = 'Hello, world!';
SET @crypt = DES_ENCRYPT(@plain);

-- Display the encrypted string
SELECT HEX(@crypt) AS encrypted;

The output is:

+------------------------------------+
| encrypted                          |
+------------------------------------+
| 80F2A42004018344DBD8BD69BC666FA1A2 |
+------------------------------------+

The DES_ENCRYPT() function returns a binary string that can be decrypted using the DES_DECRYPT() function without a key, because it uses the same key that was stored in the des_key_file system variable.

Example 3: Encrypting and decrypting a string with a key

In this example, we use the DES_ENCRYPT() and DES_DECRYPT() functions to encrypt and decrypt a string with a key. We assume that the des_key_file system variable is set to a file that contains the key.

-- Set a key
SET @key = 'secret';

-- Encrypt a string with the key
SET @plain = 'Hello, world!';
SET @crypt = DES_ENCRYPT(@plain, @key);

-- Decrypt the string with the same key
SET @decrypt = DES_DECRYPT(@crypt, @key);

-- Display the original and decrypted strings
SELECT @plain AS original, @decrypt AS decrypted;

The output is:

+---------------+---------------+
| original      | decrypted     |
+---------------+---------------+
| Hello, world! | Hello, world! |
+---------------+---------------+

The DES_DECRYPT() function returns the original string that was encrypted using the DES_ENCRYPT() function with the same key.

Related Functions

Some of the functions that are related to the DES_ENCRYPT() function are:

• DES_DECRYPT(): This function decrypts a string that was encrypted using the DES_ENCRYPT() function. It uses the DES algorithm, which is a symmetric-key block cipher. It is the inverse of the DES_ENCRYPT() function. For example, DES_DECRYPT(DES_ENCRYPT('Hello, world!', 'secret'), 'secret') returns Hello, world!.
• AES_ENCRYPT(): This function encrypts a string using the Advanced Encryption Standard (AES) algorithm and returns a binary string. It is similar to the DES_ENCRYPT() function, but it uses a more secure and modern algorithm. For example, AES_ENCRYPT('Hello, world!', 'secret') returns a binary string that can be decrypted using AES_DECRYPT() with the same key.
• AES_DECRYPT(): This function decrypts a string that was encrypted using the AES_ENCRYPT() function. It uses the AES algorithm, which is a symmetric-key block cipher. It is similar to the DES_DECRYPT() function, but it uses a more secure and modern algorithm. For example, AES_DECRYPT(AES_ENCRYPT('Hello, world!', 'secret'), 'secret') returns Hello, world!.

Conclusion

The DES_ENCRYPT() function is a useful function for encrypting a string using the DES algorithm, which is a symmetric-key block cipher. It can be used for protecting sensitive data, such as passwords, credit card numbers, or personal information. The DES_ENCRYPT() function accepts a string that represents the data to be encrypted and an optional string that specifies the key to use for encryption. It returns a binary string that represents the encrypted data. The DES_ENCRYPT() function is compatible with other string functions, such as DES_DECRYPT(), AES_ENCRYPT(), and AES_DECRYPT().